More Than 75 Percent Decline Over 27 Years In Total Flying Insect Biomass

Insects are disappearing(CCSS Level: Grade 10, Words: 307)

Oct 20, 2017 Science & Technology

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Loss of insects is certain to have adverse effects on ecosystem functioning, as insects play a central role in a variety of processes, includingpollination, nutrientcycling and providing a food source for higher levels of the food chain, such as birds, mammals and amphibians. For example, 80% of wild plants are estimated to depend on insects for pollination, while 60% of birds rely on insects as a food source. The ecosystem services provided by wild insects have been estimated at $57 billion annually in the USA alone. Clearly, preserving insect numbers and diversity should be a major conservation priority.

However, in just 3 decades, insect populations in German nature reserves, for example, have plummeted by more than 75%, according to a new study. The reasons for the decline aren't clear, but the pattern is consistent over large areas of western and northern Germany, from the region around Bonn and Cologne to the countryside south of Berlin.

For 27 years, members of the Krefeld EntomologicalSociety near Dusseldorf have monitored flying insect populations - everything from parasitic wasps to hover flies and wild bees - in dozens of nature reserves.

In recent years, they noticed a steep decline in their catch, with biomass dropping by some 82% in the summer when insect populations normally peak. Their attempts to match the decline with changes in weather, landscapes, and plant coverage - in collaboration with scientists in the Netherlands and the United Kingdom - don't explain the loss.

The scientists think that intensive agriculture surrounding the nature reserves has played a role, but they don't have data on factors such as pesticide use in neighbouring fields. The rapid drop is likely having wider-ranging effects on plants and other animals, such as insect-eating birds. The researchers say that better monitoring of these very important, but overlooked, members of the living world is urgently needed.